Rack and pinion drives turn rotary motion into linear movement.
In order to design the rack, the following parameters are necessary:
Torque on pinion, RPM of gear, linear speed of rack, linear force, any space restrictions ergo diameter and width of gear and rack, duty cycle and expected life. For positioning applications the rack drive might have to be hardened and ground to achieve higher accuracy.
Environment issues like humidity, dust, salinity, acidity or any other factors that might have an impact of the proper function of a rack and gear drive need to be considered in the layout.
Stainless steel racks and gear drives need to be derated according to available data.